I should add that using heated VG with freebase nicotine is a recipe for a nasty juice. Heat will oxidize nicotine and make it harsh and it will in turn oxidize your flavorings. Leave it out.
When I started mixing people were touting the crockpot methods and also a heated ultrasonic cleaner. Results were all over the place and I am convinced that the cause for bad results was the added nicotine. I am also confident that these people were on the right track heat wise.
I found these statements really interesting from The Flavorah Recipe book; (page 15)
“much of what has become known as the “steeping” process by ejuice makers is actually accelerated oxidation of the flavorings caused by the addition of freebase nicotine.”…If nicotine is not added, this undesirable oxidation does not occur and the initial flavoring profile of the recipe will be maintained more consistently over time."…The recipes in this book all include a recommended aging
time from the creator. This is not a hard rule, and there is no wrong answer when it comes to aging eliquids. However, it’s highly recommended that stirring, shaking, and/or homogenizing immediately takes place after mixing."
Nothing is said about heating though in the other thread I pointed to many examples by experienced or pro mixers that have been recommending 60C for several years.
As far as Sous Vide I can’t imagine a better way to bring bottles of juice up to temp with the circulating water. I will likely buy one. I use a small crock pot that stays a steady 60C but can see that this would work much better.